Cactus V6 IIs User Manual page 9

The V6 IIs transceiver comes with a multi-system shoe that supports TTL pass-
through.
While the V6 IIs does not command slave flashes to fire TTL exposures wirelessly, it is
designed to pass TTL signal from camera to flash via the transmitter (TX) and vice
versa.
The hot shoe supports TTL pass-through of Sony systems. Make sure that camera and
flash unit belong to the same TTL system.
With TTL pass-through, the TTL flashes behave as they would when directly
connected to the camera hot shoe. The V6 IIs will work as a wireless flash
commander while supporting all the automatic features (e.g., automatic flash output
via TTL metering, AF assist light, second curtain sync, high speed sync/FP shutter)
provided by the TTL flash system.
To enable TTL pass-through in the V6 IIs TX, press and hold for 2 seconds. The
LCD will show the TTL pass-through indicator at the left bottom corner where the
channel indicator used to be.
(image)
In TTL pass-through mode, the V6 IIs TX cannot control the power level of the flash
attached.
To disable the TTL pass-through mode, press and hold for 2 seconds. The TTL
pass-through indicator will be replaced by the channel indicator on the LCD.